Make Mongo & JDBC modules as auto-config

* Also make a `spring-splitter-function` as an auto-config since it used in Mongo & JDBC suppliers
* Fix all their Checkstyle violations

function/spring-splitter-function/src/main/java/org/springframework/cloud/fn/splitter/SplitterFunctionConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2020 the original author or authors.
+ * Copyright 2011-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,14 +23,13 @@ import java.util.function.Function;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 
+import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
-import org.springframework.context.annotation.Configuration;
-import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.integration.channel.ReactiveStreamsSubscribableChannel;
 import org.springframework.integration.file.splitter.FileSplitter;
 import org.springframework.integration.splitter.AbstractMessageSplitter;
@@ -39,7 +38,13 @@ import org.springframework.integration.splitter.ExpressionEvaluatingSplitter;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageChannel;
 
-@Configuration
+/**
+ * Auto-configuration for Splitter function.
+ *
+ * @author Artem Bilan
+ * @author Soby Chacko
+ */
+@AutoConfiguration
 @EnableConfigurationProperties(SplitterFunctionProperties.class)
 public class SplitterFunctionConfiguration {
 
@@ -50,7 +55,7 @@ public class SplitterFunctionConfiguration {
 		messageSplitter.setApplySequence(splitterFunctionProperties.isApplySequence());
 		ThreadLocalFluxSinkMessageChannel outputChannel = new ThreadLocalFluxSinkMessageChannel();
 		messageSplitter.setOutputChannel(outputChannel);
-		return message -> {
+		return (message) -> {
 			messageSplitter.handleMessage(message);
 			return outputChannel.publisherThreadLocal.get();
 		};
@@ -59,8 +64,7 @@ public class SplitterFunctionConfiguration {
 	@Bean
 	@ConditionalOnProperty(prefix = "splitter", name = "expression")
 	public AbstractMessageSplitter expressionSplitter(SplitterFunctionProperties splitterFunctionProperties) {
-		return new ExpressionEvaluatingSplitter(
-				new SpelExpressionParser().parseExpression(splitterFunctionProperties.getExpression()));
+		return new ExpressionEvaluatingSplitter(splitterFunctionProperties.getExpression());
 	}
 
 	@Bean

function/spring-splitter-function/src/main/java/org/springframework/cloud/fn/splitter/SplitterFunctionProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2020 the original author or authors.
+ * Copyright 2019-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,10 +19,11 @@ package org.springframework.cloud.fn.splitter;
 import jakarta.validation.constraints.AssertTrue;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.expression.Expression;
 import org.springframework.validation.annotation.Validated;
 
 /**
- * Configuration properties for the Splitter Processor app.
+ * Configuration properties for the Splitter function.
  *
  * @author Gary Russell
  * @author Artem Bilan
@@ -34,7 +35,7 @@ public class SplitterFunctionProperties {
 	/**
 	 * A SpEL expression for splitting payloads.
 	 */
-	private String expression;
+	private Expression expression;
 
 	/**
 	 * When expression is null, delimiters to use when tokenizing {@link String} payloads.
@@ -63,11 +64,11 @@ public class SplitterFunctionProperties {
 	 */
 	private boolean applySequence = true;
 
-	public String getExpression() {
+	public Expression getExpression() {
 		return this.expression;
 	}
 
-	public void setExpression(String expression) {
+	public void setExpression(Expression expression) {
 		this.expression = expression;
 	}
 

function/spring-splitter-function/src/main/java/org/springframework/cloud/fn/splitter/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * The Splitter function auto-configuration support.
+ */
+package org.springframework.cloud.fn.splitter;

function/spring-splitter-function/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -0,0 +1 @@
+org.springframework.cloud.fn.splitter.SplitterFunctionConfiguration

function/spring-splitter-function/src/test/java/org/springframework/cloud/fn/splitter/SplitterFunctionApplicationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2020 the original author or authors.
+ * Copyright 2011-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -40,7 +40,7 @@ public class SplitterFunctionApplicationTests {
 	@Test
 	public void testExpressionSplitter() {
 		List<Message<?>> messageList = this.splitter.apply(new GenericMessage<>("hello,world"));
-		assertThat(messageList).extracting(m -> m.getPayload().toString()).contains("hello", "world");
+		assertThat(messageList).extracting((m) -> m.getPayload().toString()).contains("hello", "world");
 	}
 
 	@SpringBootApplication